Lighting designed to illuminate vertical surfaces such as walls typically is called wall-wash lighting. Wall-wash lighting devices commonly include a light source, a power supply, and a mounting mechanism. A wall-wash lighting device mounted above a substantially vertical surface to be illuminated is classified as a down light. A wall-wash lighting device positioned below a substantially vertical surface to be illuminated is called an up light. While presently available ceiling-, floor-, or wall-mounted wall-wash lighting devices are capable of illuminating wall surfaces, problems in design still remain.
Most of the existing wall-wash lighting devices provide an illumination pattern of non-uniform light intensities when projected upon vertical wall surfaces. Specifically, existing wall-wash lighting devices suffer from strong illumination near the light source and a weakening, parabolic-shaped lighting pattern as the projection distance from the light source increases. Use of light emitting diodes (LEDs) in the light source of a wall-wash lighting device may compound the problem of non-uniform illumination. By the nature of their design and operation, LEDs tend to emit light in a more directional manner than a conventional light source. For example, incandescent light bulbs typically emit light at a uniform luminous intensity level in all directions (360 degree spherical arc about the filament). By contrast, an LED module in a luminaire typically emits light over a cone of 120 to 150 degrees. As a result, even use of a globe-shaped optic to shape the emissions of an LED may not produce an equal distribution of light.
Nonetheless, digital lighting technologies such as LEDs offer significant advantages over legacy lamps (including better lighting quality, longer operating life, and lower energy consumption). Therefore, equipping wall-wash lighting devices with LEDs remains a design goal in the lighting industry. To achieve broader and more uniform illumination patterns using LEDs, most of the commonly available wall-wash lighting devices employ physically larger components involved in light emission or projection. However, this design trade-off often results in a wall-wash lighting device that may deliver acceptable illumination, but that also presents an obtrusive and aesthetically unappealing appearance as installed. This is especially true where a large wall-wash lighting device is deployed in a surface-mount configuration.
Powering wall-mount lighting devices also may pose challenges for both the designer and manufacturer. Because lighting devices must connect to a power supply to operate, the designer faces the choice of either extending electrical wire behind a wall to a point where a wall-mount lighting device is to be mounted, or covering or otherwise minimizing the exposure of unsightly power cables extending from the wall-mount lighting device to the nearest standard double-plug wall outlet. Even if a power outlet is available on a wall surface at the position desired for mounting of a wall-wash light lighting device, space behind the device often is reserved to stow excess electrical wiring without preventing flush mounting of the lighting device upon the plane defined by the wall surface.
Because lighting devices may be purchased for use with differing power supply systems (e.g., 120V 15 amp in North America, 240V 15 amp in Europe), the manufacturer faces the challenge of designing an affordable wall-wash lighting device that may be used effectively and safely across a broad landscape of potentially profitable markets. Additionally, a manufacturer's choice of light sources also places limits on power circuitry present in a lamp design. For example, conventional light sources typically require AC power. LEDs, however, are low-voltage light sources that require constant DC voltage to operate optimally and, therefore, must be carefully regulated. Too little current and voltage may result in little or no light. Too much current and voltage can damage the light-emitting junction of the LED. Consequently, LEDs are commonly supplemented with individual power adapters to convert AC voltage to the proper DC voltage, and to regulate the current flowing through during operation to protect the LEDs from line-voltage fluctuations.
Controlling the operation of lighting devices typically is accomplished by a user manually manipulating a switch, thereby engaging or disengaging an electrical current flowing to the lighting device. Attempts to remotely control operation of lighting devices typically involve inclusion of a radio receiver which may receive light source manipulation commands (including “on” and “off”). However, such radio receivers typically require an antenna located within the lighting device. Due to the nature of light-generating and heat-generating elements (particularly in an LED-based lighting device), as well as components included to dissipate the generated heat, the radio signal that may be received by the radio receiver may be attenuated. The attenuation of the signal may result in a substantially decreased range in which the LED-based lighting device may communicate with the remote control, thereby decreasing the practicality and deployment flexibility of the lighting device.
The lighting industry is experiencing advancements in LED applications, some of which may be pertinent to certain aspects of wall-wash lighting devices.
U.S. Pat. No. 7,659,674 to Blackwell et al. is directed to an LED-based night light device that supports a wall-mount configuration, and that delivers increased illumination beam width through employment of one or more of reflectors, optics, and multiple LEDs. The disclosure includes an associated method for wirelessly controlling the lighting module using a network. However, the disclosure presumes the availability of power delivery components (e.g., power plug, AC-DC converter) that are suitable for a specific external power source.
U.S. Patent Publication No. 2012/0320572 to Fisher et al. discloses a power source for an LED bulb that receives line current as its input, and supplies low voltage DC as its output. The power source is arranged to reduce the input voltage from 120 vAC to a low DC voltage (e.g., 12 vDC). However, the disclosed power source presumes conductors (e.g., wiring) extending from the wall receptacle to the LED-based lamp. Such visible conductors are not aesthetically pleasing for wall-mount applications.
U.S. Patent Publication No. 2012/0326623 to Fatt et al. discloses a socket adapter for an LED lamp that includes an adaptor body and an AC-DC converter disposed in the adapter body. The socket adapter supports various base configurations for attaching the socket adapter to an AC power source. However, the disclosed socket adapter only supports a single input power type, as defined by the pairing of the base configuration and the matching on-board converter.
A need exists for an LED-based wall-wash lighting device that may provide a large and substantially uniform wall-wash illumination pattern, while at the same time presenting an unobtrusive and clean appearance when installed. Additional improvements may be made to support diverse power supplies and connection means prevalent in major target markets, and to facilitate remote control of the operation of the wall-wash lighting device.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.